Cooling dynamos.



R. RUDENBERG & A. ZEHRUNG.

COOLING DYNAMOS.

APPUCATION HLED IUD/13,1915.

ed Feb. 1, 1916.

1 SHEETS-SHEET I. 7 I797.

Patent UNITED STATES PATENT OFFICE.

REINHOLD RIIDENBERG, OF CHARLOTTENBURG, AND ALBERT ZEHRUNG, OF BERLIN- WILMERSDORF, GERMANY, ASSIGNORS T0 SIEMENS SCI-IUCKERT WERKE G. M. B. 11., 0F BERLIN, GERMANY, A CORPORATION OF GERMANY.

COOLING DYNAMOS.

Application filed July 13,

To all whom it may concern:

Be it known that we, REINHOLD Rr'innN- BERG and ALBERT ZEHRUN German citizens, and residents of Charlottenburg, near Berlin, Germany, and Berlin-Vilmersdorf, Germany, respectively, have invented certain new and useful Improvements in Cooling Dynamos, of which the following is a specification.

In electrical machines having artificial cooling, such as turbo-generators it has be come practice to discard one-sided'cooling and employ doublesided cooling instead thereof, since in this case with the same heat ing of the discharging air and the parts of the machine the width of the same and therewith the output can be doubled. For further increasing the output of the ma chine it has been proposed to employ hollow stator conductors through which cooling air is conveyed. In this case, however, a doublesided cooling is connected with great difficulties as the required lateral discharge opening for the air will necessitate an interruption of the insulating wrapping of the conductor. This weakening of the insulation and consequent increase of danger of flash-overs at inaccessible places of the winding, however, is not permissible. According to this invention therefore the hollow conductors .of the stator are cooled throughout one-sided, while in other respects a. doublesided cooling is employed for the machine, so that every interruption of the insulation along the conductor will be avoided.

The conductors which are cooled in a one sided manner are preferably arranged intwo groups and are cooled by means of a cooling medium passing through said groups in opposite directions in order to improve the cooling of the entire machine. In this case the conductors of either group may be taken together either individually or in a definite combination, such as for instance by taking together those conductors which are of similar mechanical construction, for instance the conductor of each phase of the windings.

Figure 1 is a diagrammatic section of one embodiment of our invention, parts being broken away and parts shown in elevation; Figs. 2 and 3 are sectional details. of the same; Fig. 4 is a fragmentary diagrammatic Specification of Letters Patent.

Patented Feb. 1, 1916.

1915. Serial No. 39,680.

section of another embodiment, parts being shown in elevation; Figs. 5 and 6 are diagrammatic plan views showing different arrangements of the conductors; Fig. 7 is a transverse section of one form of conductor; F 1g. 8 is a diagram in elevation of another embodiment; Fig. 9 is a diagrammatic elevation of a modification, parts being broken away and parts shown in section; Fig. 10 1s a section on the line X-X, Fig. 9: Fig. 11 1s a section on the line XI XI, Fig. 9, the tube 11 being shown in bottom plan; Fig. 12 is a section on line XII-XII, Fig. 9; Fig. 13 is a. section on line XIIIXIII, Fig. 9.

Fig. 1 showsour invention applied to a. turbo-generator. The pressure chambers 2 are supplied with cooling air by means of the two fans 1 which are mounted on the axle of the machine, said cooling air being carried from said chambers in the direction as indicated by arrows through the axial and radial channels for cooling the stator from both sides. Besides said pressure chambers 2 there are provided special airdischarging chambers 3 and the separating wall 4 between said pressure chambers and said air-discharging chambers is for instance made from insulating material through which the stator conductors are carried. The front hollow conductor 5 is so positioned that it will connect the left pressure space with the right air-discharging space 3, while the next conductor 6 is displaced toward the left, so that it will connect the right pressure chamber with the left airdischarging chamber 3. In this manner the two conductors are cooled by a stream of air in opposite directions.

The air-discharging chambers 3 are shown as ring-shaped channels near the lateral parts of the casing and may be in communication with any kind of air-discharging channels, for instance in the base or in the casing of the machine. The air-discharging spaces 3 also may direclly open into the engine room or they mav be entirely omitted in case it is permissble to freely expose the discharge openings of the stator conductors.

Good insulation of the conductors at the separating walls is very essential and may be carried out in various manners. The wall itself may be made from insulating material or the conductor may be carried through the wall and only insulated therefrom or it may be prolonged by means of an insulating connecting. tube as far as to the wall. In Fig. 2 we have shown a manner of prolonging the thick-walled hollow conductor 6 by a thin-walled metal or insulating tube 8 as far as to the separating wall l, Fig. 3 shows a construction whereby a flange 9 is used at the separating wall which flange extends toward the conducting tube 6 leaving only a small distance between the same. The losses which are due to the gap are immaterial in this case as for increasing the insulation a complete separation of the stator winding from .thewall construction of the air chambers is attained.

While according to the construction of Fig. 1 the winding ends 11 are entirely placed within the pressure chambers 2, so that the winding ends are surrounded by the cooling air, the same are partly positioned within the pressure space and partly in the air-discharging space according to the construction of Fig, 4. The middle parts 12 of the windingggends therefore must be carried through the separating w all l.

In Figs. 5 and 6 we have shown the position of the stator conductors for a winding whereby the conductors regarding the way of cooling are subdivided in groups of three or two bars. The first mentioned grouping is suited for a three-hole winding and the latter for a two-hole winding. The arrangement of the air chambers in .the first case corresponds to Figs. 1 and 4 and in the second case the individual groups 6 and 7 of the stator conductors are carried to especial air-discharging tubes 13 which lead the cooling air after being heated through the pressure space toward the outside. Caps 14 which are preferably made from insulating material collect cooling air from the several tubes which are cooled by evenly directed streams of air. Each two conductors which are passed by oppositely directed streams of air may in every case be arranged in different slots as well as in the same slot. The construction according to our invention is also applicable in a proper manner if the air channel in the winding is also partly or wholly surrounded by the insulating wrapping instead of the material of the conductor itself. Fig. 7 shows a conductor 15 of this kind having a double T-shaped crosssection and an insulating wrapping 16, said wrapping forming the limiting walls for the two lateral air channels 17 whereby preferably a hollow conductor is formed.

- lln Fig. 8 we have shown a further im provement which consists in an arrangement whereby the cooling air passing through the hollow conductors from the one side of the machine is united with the stream of fresh air which enters on the other side of the machine. By this the construction is essentially simplified and rendered cheaper by dispensing with special air discharging chambers and conduits. In Fig. 8 a turbogenerator with such an arrangement is shown diagrannnatically in section. The main streams of air enter from the left and from the right in the direction of the arrows into the chambers 3 on either side of the machine. The two fans 1 which are provided on the rotor press the air into the pressure chambers 2 on either side of the machine, whence the streams of air will pass the cooling channels in the stator also as indicated by the arrows. The cooling air is sucked into the air channels of the rotor from the chambers 3 by the efiect of the rotation of the rotor. The direction of motion of the air in these channels is also indicated by arrows. The pressure chambers 2 are separated from the suction chambers 3 by the walls 4:. These walls serve the same as in the former constructions for the passage of the hollow conductors or hollow windings 5 and 6. Both bars, the same as in the former constructions, are of even length but displaced relatively to each other so that the bar 5 will communicate with the pressure space on the left side and with the suction space on the right side, while the bar 6 will communicate with the pressure space on the right side and the suction space on the left side. The bars consequently will be passed by streams of air which are oppositely directed. At the discharge openings of both bars the cooling air will be mixed with the stream of fresh air which enters at this point. This mixing and the slight increase of temperature of the stream of fresh air which is caused thereby is of no disadvantage for the entire cooling efiect of the machine as only a small part of the entire cooling medium will pass through the hollow conductors.

According to Figs. 1 and 4:, the cooling air enters the fans 1 from opposite directions along the axis of the shaft and is thrown into "the pressure chambers 2 on either side. From said pressure chambers 2, such air passes entirely through the stator from one side to another into the discharge chambers 3 which have discharge outlets or ducts (not shown in Fig. 1). In Fig. l, the discharge chambers 3 open into a centrally disposed annular chamber 20 which is open to the outer air. In addition, it will be seen that according to Figs. 1 and 4:, cooling air passes inwardly from the pressure chambers 2 through other channels 18 which open into radially arranged channels 19 discharging outwardly into the chamber 20.

According to Fig. 8, the cooling air enters suction chamber 3 on either side from below and is forced by the fan 1 into pressure chamber 2 from which portions of said cooling air pass through tubes 5 and 6 into the suction chambers 3. Other portions of the cooling air in chambers 2 pass inwardly from opposite sides from passages 18 to the radially arran ed passages 19 which discharge outwarddy into the centrally arranged chamber 20 which opens downwardly ac cording to this embodiment. At the same time cooling air from chambers 3 pass from opposite sides through passages 21 in the rotor into radially arranged channels 22 from which the air is expelled by the movement of said rotor. Fig. 9 shows a construction according to our invention for such windings whereby the individual winding parts are mounted in one slot in certain distances from each other, so that air channels will be present between the same. In Fig. 9

as an example a winding is shown which consists of three strands 8, 9 and 10 which strands are spaced apart within the slot in order to form the aforementioned air channels. At the winding ends the strands may be placed together without any intermediate.

space which will increase the stiffness of the winding. On the left side the winding end is positioned within the pressure space 2, so that the air will immediatel enter between the several strands into the air channels. On the right side the cooling air discharging from the winding must be carried through the pressure space 2 and through the wall 4 as far as to the suction space 3 for the fresh air. For this purpose a tube 11 for instance of insulating material is provided on the winding which comes out of the stator iron. Said tube forms a prolongation of the covering which surrounds the partial conductors 8, 9 and 10 and is enlarged laterally as shown best in Figs. 11 and 12 to provide suitable air channels around the partial conductors where they bend to pass with an airtight joint through the wall of the tube. The

cooling air streaming through the slot will consequently enter into this tube 11 and will be conveyed from here to the suction space 3 for the fresh air. According to the form of the winding end and the position and form of the air channels in the slot said tube 11 must be so constructed that it will permit an easy discharge of the cooling air at the same time providing an air-tight. closure against the winding and the winding ends.

Having thus described our invention we claim as new and desire to secure by Letters Patent of the United States 1. vIn a dynamo electric machine, the combination with a stator provided with hollow conductors extending continuously from one side to the other of said stator, of means for sending cooling air through some of said conductors in one direction, and means for sending cooling air through others of said conductors in the opposite direction.

2. In a dynamo electric machine the combination of a stator with hollow conductors therein, means for supplying cooling air to both sides of said stator, communicating spaces connecting said-hollow conductors in groups for passing the cooling air through either one of said groups in one direction and in opposite directions in different groups.

3. In a dynamo electric machine the combination of a stator with hollow conductors, means for supplying cooling air to both sides of said stator, pressure and discharge chambers on either side of said stator, said chambers communicating with each other on different sides of said stator by means of said hollow conductors, and an insulating separating wall between pressure and air discharging chambers on either side of said stator.

4. In a dynamo electric machine the combination of a stator with hollow conductors therein, means for supplying cooling air to both sides of said stator, pressure and discharge cha-mber's on either side of said stator, said chambers on different sides of said stator communicating through said hollow conductors, tubes connecting the ends of some of said conductors to said air discharge chamber on one side of said stator, other tubes connecting others of said conductors to said air discharge chamber on the other side of said stator, and an insulating wall between the pressure and air discharge chambers on each side of the stator.

5. In a dynamo electric machine the combination of a stator with hollow conductors therein, means for supplying cooling air to both sides of said stator, pressure and discharge chambers on either side of said stator, said chambers on dilierent sides of said stator communicating through said hollow conductors, and tubes adapted to the'ends of said conductors, said tubes connecting said hollow conductors with the air discharging space through said pressure chambers, said tubes being'fixed upon the separating wall between said pressure and said air discharge chambers.

6. In a dynamo electric machine the combination of a stator with hollow conductors therein, means for supplying cooling air to both sides of said stator, pressure and dis-- charge chambers on either side of said stator, and connections for said hollow conductors whereby cooling air will be carried through said conductors in opposite directions in individual conductors, and a discharge tube common to a plurality of adja cent conductors.

7. In a dynamo electric machine the combination of a stator having hollow conductors therein, means for supplying cooling air to said stator from both sides, and air conveying chambers connected to said hollow 4 gimme conductors for carrying cooling air through sides which will unite itself with said coo1- said conductors in opposite directions in ing air.

groups of said conductors and for causing REINHOLI) RUDENBERG. the cooling air coming from one side of said ALBERT ZEHRUNG. machine to pass through said hollow con- Witnesses:

duotors to the other side of said machine, and WOLDEMAR HAUPT,

means for supplying fresh airito said other HENRY HASPER.

Copies of this patent'may'be obtained for five cents eachyby addressing the Commissioner of Patents. Washington. D. G." 

